The invention relates to the cooling of motor vehicles.
It relates more particularly to a device for cooling a vehicle with an electric motor powered by a fuel cell.
Such a device can be applied to vehicles driven solely by an electric motor, as well as to vehicles of the hybrid type which are capable of being driven either by an electric motor or by a motor of another type, in particular by an internal-combustion engine.
In a motor vehicle of the abovementioned type, it is necessary to provide for the cooling of the fuel cell, given that the latter is generally fed with hydrogen and with air under pressure, which are usually at a temperature higher than the ambient temperature.
It is also necessary to provide for the cooling of the electric motor proper, as well as of its power control and of other accessories, as appropriate.
Cooling devices of this type are already known, which comprise a main loop with a main radiator for cooling the fuel cell and a secondary loop with a secondary radiator for cooling at least the electric motor.
In the known devices, the main loop and the secondary loop are formed as two separate circuits which are each traversed by a specific cooling fluid and which each comprise an electric pump, an expansion chamber and regulation means. The main reasons for the existence of two separate circuits relate principally to the fact that these two circuits have to operate at different levels of temperature and of throughput. In fact, the main circuit has to operate at a temperature and at a throughput which are higher than the secondary circuit.
Because of the existence of two separate loops or circuits, the cooling device includes a large number of components, which has the drawback especially of complicating the production of the device and of increasing its bulk.
The object of the invention is especially to overcome the abovementioned drawbacks.
It aims in particular to procure a cooling device of simplified structure comprising a reduced number of components.
To that end the invention proposes a cooling device of the type defined in the introduction, in which the main loop and the secondary loop form part of the same circuit which is traversed by a single cooling fluid and which comprises a section common to the two loops on which a common pump is mounted, and in which at least one regulation valve is provided which is suitable for sharing the refrigerant fluid between the two loops according to a chosen law.
Thus the cooling device of the invention groups together the main loop and the secondary loop within the same circuit which is traversed by a single refrigerant fluid, under the action of a common pump.
This makes it possible to reduce the number of components of the circuit, and, furthermore, to allow the main loop and the secondary loop to function with their own specific features, in particular as regards the level of throughput and of temperature, especially by virtue of a specific regulation valve.
In a first embodiment of the invention, the common section comprises only the pump, and the device further comprises a single regulation valve placed upstream of the pump.
Advantageously, this takes the form of a four-way valve which comprises a first inlet linked to the main loop downstream of the main radiator, a second inlet linked to a bypass from the main loop which goes round the main radiator, a third inlet linked to the secondary loop and an outlet linked to the common section.
In a second embodiment, the common section comprises the pump and the main radiator, and the device further comprises a first regulation valve placed downstream of the main radiator and upstream of the pump, as well as a second regulation valve placed downstream of the pump.
Advantageously, the first regulation valve is a three-way valve which comprises a first inlet linked to the main loop downstream of the main radiator, a second inlet linked to a bypass from the main loop which goes round the main radiator and an outlet linked to the common section. The second regulation valve is advantageously a three-way valve which comprises an inlet linked to the common section, a first outlet linked to the main loop upstream of the fuel cell and a second outlet linked to the secondary loop upstream of the secondary radiator, in such a way that the secondary loop is mounted in parallel with the fuel cell.
In a third embodiment of the invention, the main radiator is divided into a first part and a second part, the common section comprises the pump, the first part of the main radiator and the secondary radiator, while the second part of the main radiator forms part of the secondary loop. The device then further comprises a regulation valve placed upstream of the main radiator.
In this third embodiment of the invention, a four-way valve is advantageously used, which comprises a first inlet linked to the main loop downstream of the fuel cell, a second inlet linked to the secondary loop downstream of the second part of the main radiator, a first outlet linked to the common section upstream of the first part of the main radiator and a second outlet linked to a bypass from the main loop which goes round the first part of the main radiator.
In this third embodiment of the invention, the first part of the main radiator and the secondary radiator can be mounted either in series or in parallel.
Advantageously, whatever the chosen embodiment, the device further comprises an expansion chamber mounted in the main loop. It may further comprise at least one air heater mounted in the main loop in order to provide for the heating of the passenger compartment of the vehicle.
Advantageously, the device further comprises a motor-driven fan unit associated with the main radiator, or else with the secondary radiator.